The ups and downs of life: population expansion and bottlenecks of helminth parasites through their complex life cycle

Parasitology ◽  
2015 ◽  
Vol 142 (6) ◽  
pp. 791-799 ◽  
Author(s):  
ROBERT POULIN ◽  
CLÉMENT LAGRUE
Keyword(s):  
Life Stage ◽  
Population Expansion ◽  
Positive Association ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Total Density ◽  
Life Stages ◽  
Helminth Parasites ◽  
Trophic Transmission ◽  
Downstream Target

SUMMARYThe fundamental assumption underpinning the evolution of numerous adaptations shown by parasites with complex life cycles is that huge losses are incurred by infective stages during certain transmission steps. However, the magnitude of transmission losses or changes in the standing crop of parasites passing from upstream (source) to downstream (target) hosts have never been quantified in nature. Here, using data from 100 pairs of successive upstream–downstream life stages, from distinct populations representing 10 parasite species, we calculated the total density per m2 of successive life stages. We show that clonal amplification of trematodes in their first intermediate host leads to an average 4-fold expansion of numbers of individuals at the next life stage, when differences in the longevity of successive life stages are taken into account. In contrast, trophic transmission to the definitive host results in almost no numerical change for trematodes, but possibly in large decreases for acanthocephalans and nematodes, though a correction for longevity was not possible for the latter groups. Also, we only found a positive association between upstream and downstream stage densities for transmission involving free-swimming cercariae in trematodes, suggesting a simple output-recruitment process. For trophic transmission, there was no coupling between downstream and upstream parasite densities. These first quantitative estimates of ontogenetic rises and falls in numbers under natural conditions provide new insights into the selective pressures acting on parasites with complex cycles.

scholarly journals Do traits separated by metamorphosis evolve independently? Concepts and methods

2019 ◽  
Vol 286 (1900) ◽  
pp. 20190445 ◽  
Author(s):  
Julie Collet ◽  
Simon Fellous
Keyword(s):  
Life Stage ◽  
Genetic Correlations ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Multivariate Methods ◽  
Life Stages ◽  
Complex Life Cycles ◽  
Quantitative Characters ◽  
Genetic Patterns ◽  
G Matrices

Despite the ubiquity of complex life cycles, we know little of the evolutionary constraints exerted by metamorphosis. Here, we present pitfalls and methods to answer whether animals with a complex life cycle can independently adapt to the environments encountered at each life stage, with a specific focus on the microevolution of quantitative characters. We first discuss challenges associated with study traits and populations. We further emphasize the benefits of using a combination of approaches. We then develop how multivariate methods can limit several issues by revealing genetic patterns that are invisible when only considering trait-by-trait genetic correlations. Finally, we detail how Lande's work on sexual dimorphism can be applied in measuring G matrices across life stages. The methods and tools described here will contribute towards building a predictive framework for trait evolution across life stages.

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

Autonomy and integration in complex parasite life cycles

Parasitology ◽  
2016 ◽  
Vol 143 (14) ◽  
pp. 1824-1846 ◽  
Author(s):  
DANIEL P. BENESH
Keyword(s):  
Life Cycle ◽  
Holistic Approach ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Functional Specialization ◽  
Life Stages ◽  
Free Living ◽  
New Host ◽  
Complex Life Cycles ◽  
Life Cycle Stages

SUMMARYComplex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

scholarly journals The evaluation of feeding, mortality and oviposition of poultry red mite (Dermanyssus gallinae) on aging hens using a high welfare on-hen feeding device

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 1266
Author(s):  
Francesca Nunn ◽  
Kathryn Bartley ◽  
Javier Palarea-Albaladejo ◽  
Alasdair J. Nisbet
Keyword(s):  
Adult Female ◽  
Life Stage ◽  
Positive Association ◽  
Dermanyssus Gallinae ◽  
Life Stages ◽  
Feeding Rates ◽  
Poultry Red Mite ◽  
Clear Trend ◽  
Mite Feeding ◽  
High Welfare

A study was performed to examine any effect of hen age on the feeding ability and mortality of different life-stages of Dermanyssus gallinae [Poultry Red Mite (PRM)] when fed using a high welfare, on-hen mite feeding device. Mite feeding assays were carried out every two weeks on a cohort of five Lohman Brown hens with devices containing adult and deutonymph PRM or adult and protonymph PRM. Feeding rates and mortality of each PRM life stage and oviposition of adult female PRM were evaluated over an 18-week period. There was a significant reduction in oviposition rates of female PRM as they fed on hens of increasing age. However, no clear trend was detected between the feeding rates of all three haematophagous life stages and hen age. The same conclusion was reached regarding mite mortality post-feeding in both deutonymph and adult female PRMs, although a weak positive association was apparent between hen age and protonymph PRM mortality. This study shows that the on-hen feeding device can be used both for short term studies to assess novel anti-PRM products (new acaricides, vaccines etc.) and longer, longitudinal studies to determine longevity of the effects of such novel anti-PRM products. It also demonstrates that blood feeding by mites on older hens is less able to sustain PRM populations than feeding on younger hens. This on-hen mite feeding device directly impacts upon reduction and refinement by greatly reducing the numbers of birds required per experimental group compared to traditional PRM challenge infestation models and by eliminating the need for birds to be exposed to large numbers of mites for extended periods of time that can cause welfare concerns. This paper describes the methodology for these studies and how to assemble pouches and handle mites both before and after feeding assays.

The Influence of Life Stage on Father-Son Work Relationships in Family Companies

1989 ◽  
Vol 2 (1) ◽  
pp. 47-74 ◽  
Author(s):  
John A. Davis ◽  
Renato Tagiuri
Keyword(s):  
Life Stage ◽  
Work Relationships ◽  
Life Cycles ◽  
Life Stages ◽  
Negative Effects ◽  
Work Relationship ◽  
Fathers And Sons ◽  
The Relationship

The authors examine the relationship between the life cycles of fathers and sons who work together, concluding that the quality of the work relationship varies as a function of their respective life stages. The intersection of their individual developmental paths can have positive or negative effects on the nature of the work relationship, on the resolution of such problem issues as succession, and on productivity.

scholarly journals Comparative analysis of helminth infectivity: growth in intermediate hosts increases establishment rates in the next host

2021 ◽  
Vol 288 (1947) ◽  
Author(s):  
Spencer Froelick ◽  
Laura Gramolini ◽  
Daniel P. Benesh
Keyword(s):  
Life Cycle ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Intermediate Hosts ◽  
Cycle Progression ◽  
Recovery Rates ◽  
High Doses ◽  
Parasitic Worms ◽  
Higher Doses

Parasitic worms (i.e. helminths) commonly infect multiple hosts in succession before reproducing. At each life cycle step, worms may fail to infect the next host, and this risk accumulates as life cycles include more successive hosts. Risk accumulation can be minimized by having high establishment success in the next host, but comparisons of establishment probabilities across parasite life stages are lacking. We compiled recovery rates (i.e. the proportion of parasites recovered from an administered dose) from experimental infections with acanthocephalans, cestodes and nematodes. Our data covered 127 helminth species and 16 913 exposed hosts. Recovery rates increased with life cycle progression (11%, 29% and 46% in first, second and third hosts, respectively), because larger worm larvae had higher recovery, both within and across life stages. Recovery declined in bigger hosts but less than it increased with worm size. Higher doses were used in systems with lower recovery, suggesting that high doses are chosen when few worms are expected to establish infection. Our results indicate that growing in the small and short-lived hosts at the start of a complex life cycle, though dangerous, may substantially improve parasites' chances of completing their life cycles.

scholarly journals Cross-Life Stage Effects of Aquatic Larval Density and Terrestrial Moisture on Growth and Corticosterone in the Spotted Salamander

Diversity ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 68 ◽  
Author(s):  
Julie Charbonnier ◽  
Jacquelyn Pearlmutter ◽  
James Vonesh ◽  
Caitlin Gabor ◽  
Zachery Forsburg ◽  
...  
Keyword(s):  
Early Life ◽  
Specific Growth ◽  
Life Stage ◽  
Larval Density ◽  
Life Cycles ◽  
Life Stages ◽  
Early Life Stages ◽  
Release Rates ◽  
Specific Growth Rates ◽  
Corticosterone Release

For organisms with complex life cycles, conditions experienced during early life stages may constrain later growth and survival. Conversely, compensatory mechanisms may attenuate negative effects from early life stages. We used the spotted salamander, Ambystoma maculatum, to test how aquatic larval density and terrestrial moisture influence juvenile growth, food intake, evaporative water loss and water reuptake rates, and corticosterone levels. We conducted an outdoor mesocosm experiment to manipulate larval density and transferred metamorphosed salamanders into low and high terrestrial moisture treatments in laboratory terrariums. After the larval stage, high-density salamanders were significantly smaller and had higher corticosterone release rates than those from low-density treatments. Salamanders in the low terrestrial moisture treatment consumed fewer roaches, had lower mass-specific growth rates, higher water reuptake, and higher corticosterone release rates than salamanders in high terrestrial moisture treatments. Across moisture treatments, smaller salamanders had higher mass-specific growth rates than larger salamanders. Our results suggest that salamanders can partially compensate for competition in the larval aquatic habitat with increased growth as juveniles, but this response is dependent on terrestrial habitat quality. Thus, the persistence of early life stage effects can be an important, yet context-dependent, component of amphibian life cycles.

scholarly journals Molecular signatures of the rediae, cercariae and adult worm stages in the complex life cycles of parasitic flatworms (Psilostomatidae, Trematoda)

2019 ◽  
Author(s):  
Maksim A. Nesterenko ◽  
Viktor V. Starunov ◽  
Sergei V. Shchenkov ◽  
Anna R. Maslova ◽  
Sofia A. Denisova ◽  
...  
Keyword(s):  
Adult Worm ◽  
Related Species ◽  
Life Histories ◽  
Expression Patterns ◽  
Life Forms ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Molecular Signatures ◽  
Life Stages ◽  
Complex Life Cycles

AbstractTrematodes are one of the most remarkable animals with complex life cycles with several generations. Life histories of a parasitic flatworms include several stages with disparate morphological and physiological characteristics follow each other and infect hosts ranging from mollusks to higher vertebrates. How does one genome regulate the development of various life forms and how many genes are needed to the functioning of each stages? How similar are molecular signatures of life stages in closely related species of parasitic flatworms? Here we present the comparative analysis of transcriptomic signatures of the rediae, cercaria and adult worm stages in two representatives of the family Psilostomatidae (Echinostomata, Trematoda) -Psilotrema simillimumandSphaeridiotrema pseudoglobulus. Our results indicate that the transitions between the stages of the complex life cycle are associated with massive changes in gene expression with thousands of genes being stage-specific. In terms of expression dynamics, the adult worm is the most similar stage betweenPsilotremaandSpaeridiotrema, while expression patterns of genes in the rediae and cercariae stages are much more different. This study provides transcriptomic evidences not only for similarities and differences between life stages of two related species, but also for cryptic species inSphaeridiotrema.

scholarly journals Does a complex life cycle affect adaptation to environmental change? Genome-informed insights for characterizing selection across complex life cycle

2021 ◽  
Vol 288 (1964) ◽  
Author(s):  
Molly A. Albecker ◽  
Laetitia G. E. Wilkins ◽  
Stacy A. Krueger-Hadfield ◽  
Samuel M. Bashevkin ◽  
Matthew W. Hahn ◽  
...  
Keyword(s):  
Life Cycle ◽  
Empirical Studies ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Ecological Niches ◽  
Life Stages ◽  
Complex Life Cycles ◽  
High Fecundity ◽  
Trade Offs ◽  
Frequency Changes

Complex life cycles, in which discrete life stages of the same organism differ in form or function and often occupy different ecological niches, are common in nature. Because stages share the same genome, selective effects on one stage may have cascading consequences through the entire life cycle. Theoretical and empirical studies have not yet generated clear predictions about how life cycle complexity will influence patterns of adaptation in response to rapidly changing environments or tested theoretical predictions for fitness trade-offs (or lack thereof) across life stages. We discuss complex life cycle evolution and outline three hypotheses—ontogenetic decoupling, antagonistic ontogenetic pleiotropy and synergistic ontogenetic pleiotropy—for how selection may operate on organisms with complex life cycles. We suggest a within-generation experimental design that promises significant insight into composite selection across life cycle stages. As part of this design, we conducted simulations to determine the power needed to detect selection across a life cycle using a population genetic framework. This analysis demonstrated that recently published studies reporting within-generation selection were underpowered to detect small allele frequency changes (approx. 0.1). The power analysis indicates challenging but attainable sampling requirements for many systems, though plants and marine invertebrates with high fecundity are excellent systems for exploring how organisms with complex life cycles may adapt to climate change.

‘And all my children?’

2018 ◽  
Author(s):  
Charlotte Scott
Keyword(s):  
Early Modern ◽  
Life Stage ◽  
Early Modern Period ◽  
Life Stages ◽  
Cultural Imagination ◽  
Modern Period

Beginning with an exploration of the role of the child in the cultural imagination, Chapter 1 establishes the formative and revealing ways in which societies identify themselves in relation to how they treat their children. Focusing on Shakespeare and the early modern period, Chapter 1 sets out to determine the emotional, symbolic, and political registers through which children are depicted and discussed. Attending to the different life stages and representations of the child on stage, this chapter sets out the terms of the book’s enquiry: what role do children play in Shakespeare’s plays; how do we recognize them as such—age, status, parental dynamic—and what are the effects of their presence? This chapter focuses on how the early moderns understood the child, as a symbolic figure, a life stage, a form of obligation, a profound bond, and an image of servitude.

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